I currently have Pekins, Blue Swedes, a Mallard Drake, a Mallard X Pekin cross duck (ought to start laying in July or August.) and Pekin Swede cross drakes. Honestly I really love my pekins (can't believe I'm saying that) They lay really well, almost as well as runners, they're good foragers, they are my friendliest ducks and they grow fast. My Swede lays well too but is much smaller and shy. I had a Cayuga and I really like her for the six months I had her (darn fox

) I would like to get more one day. Runners are fun, we used to have one, I would've liked to have gotten those too. Despite what you may think my pekins are probably my toughest ducks and are very good at avoiding predators, I have not lost one to a predator as of right now. Personally I do like darker birds.
That's up to you, I have mine all mixed together and never know what I'll get, some times I'll get some Swedes sometimes I won't, sometimes it's 90% crosses and 10% Swedes other times it's 100% Pekins. I like waiting and seeing. My crosses are quite interesting. They shouldn't, I never had a problem with that, some times they will if it's a lone drake.
Lol.